US2025479A - Fuel feeding system for oil burners - Google Patents

Description

Dec. 24, 1935. L F SPEAR ET AL 2,25,479

FUEL FEEDING SYSTEM FOR OIL BURNERS Filed Feb. 25, 1933 I 42 .Fig .4

4,7 I Am LmLy/v j f' i jk Z6 BY WRGILEDUiMLER TTORNEYS.

Patented Dec. 24, 1935 UNITED STATES PATENT OFFICE FUEL FEEDING SYSTEM FOR OIL BURNERS Application February 25, 1933, Serial No. 658,644

2 Claims.

This invention relates to an improved method of and apparatus for feeding fuel to oil burners.

It is common practice to provide a pump which will feed oil to the burner at a rate somewhat in excess of the maximum rate at which fuel is consumed by the burner, and to by-pass the excess oil thus fed either to the suction side of the pump or to the supply tank. By connecting the outlet end of the by-pass pipe to the suction pipe of the pump, at a point closely adjacent the pump (usually between the strainer and the pump), a separate return pipe to the supply tank can be dispensed with and only one pipe,-from the tank to the pump,is necessary. This sort of one pipe system is satisfactory where indoor tanks are used and located at an elevation above the burner pump so that oil feeds to the pump by gravity. Where, however, the tank is located outside and underground, a single pipe system is unsatisfactory and it is usual to run the by-pass pipe back to the supply tank. A heavy suction is necessary to pull the oil from the remote and low level tank and because of the suction pull, air is more likely to be drawn into the system through joints in the suction pipe. It is even possible for small portions of the lighter fractions of the oil to be vaporized because of the vacuum produced in the suction line. The pipes need to be larger to secure the necessary mechanioal strength and because they are larger than would otherwise be necessary to carry the oil, there is room for air to accumulate, particularly in pockets in the suction line. Air is entrapped I in the oil to a certain extent and such air is more likely tobe liberated under a condition of vacuum than under pressure. It will thus be clear that air is carried along with the oil in systems where the pump has to exert a suction pull in order to draw oil to the pump.

To rid the system of such air, the separate return line to the supply tank is used. More oil than is needed for the burner is pumped and the excess oil and the air are by-passed back to the tank. The disadvantages of this practice 45 are that the returning oil causes agitation of the oil in the supply tank and a possible stirring up of the sludge therein; also that more oil than is necessary is drawn through the strainer, ne-

cessitating more frequent cleaning of the same 50 and the consumption of more power to drive the pump as the strainer clogs.

The object of this invention is to get rid of the air in the system and at the same time to return as little oil, as is compatible with the accomplishment of the above purpose, to the supply tank.

More particularly, the method of this invention provides for dividing the excess pumped oil not used by the burner and returning part of 5 it, preferably the smallest part, with the air to the supply tank and the remaining and preferably the largest and air-free part into the suction side of the pump, preferably at a point between the strainer and the pump.

With this method of operation, the work of the pump is reduced in that less oil is drawn from the tank; the strainer will not require as frequent cleaning because less oil is drawn through it; and there will be less agitation in the tank because less oil is returned to it.

The invention provides a gauged opening for predetermining the volume of oil that can flow directly back to the pump per unit of time under any given conditions of pressure and temperature. This opening can be accurately adjusted as to size and set so as to allow any desired proportion of the excess oil to flow back to the pump,-the balance returning to the tank.

The invention also has for an object the provision of a valve for closing the gauged opening when the pump is not in operation, so that when the pump is again started up it will not suck air from the return line. Such valve is supplied with an adjustable stop to limit the degree of its opening movement, whereby the effective area of said gauged opening may be varied by adjustment of the valve.

The invention also contemplates the provision of a device in which are included the necessary passages, the gauged opening and the cooperating valve, so that all that is necessary to apply the invention to a burner is to connect said device in the suction pipe of the pump and to connect the by-pass pipe and the tank return pipe thereto.

Other objects will appear as the detailed description proceeds and will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanying drawing, in which:

Fig. 1 is an elevational view showing an oil burner and a fuel feeding means therefor embodying the invention;

Fig. 2 is an exterior end elevational view of the proportioning by-pass device;

Figs. 3 and 4 are sectional views taken on the lines 3-3 and 4-4, respectively, of Fig. 2;

Fig. 5 is an elevational view, partly in section,

by piping 25 to the valve casing 29.

It also includes a suitable oil pump I3 for drawing oil from a supply tank I5 and forcing it under substantial pressure to the nozzle I9 of the burner. It is usual to interpose in the oil feed line a strainer, herein represented conventionally at H. A pipe I8 connects tank :5 to the inlet of the strainer and the outlet thereof is connected by a pipe I9 to a valve casing 29, later to be described in detail. This casing is connected by a pipe 2| to the inlet side of pump l3 and the outlet side of the latter is connected by a pipe 22 to a pressure regulating and by-pass valve 23. Such valve has an outlet connected by piping 24 to the burner nozzle I6 and a bypass outlet which is connected A pipe 23 leads from casing 29 back to the supply tank I5.

The pressure regulating valve 23 may be of any suitable type which will prevent passage of oil into the pipe 24 until the oil has been placed under a predetermined pressure, and whichwill by-pass some of the pumped oil into pipe 25 after the oil pressure has increased to another and greater predetermined pressure. As an example of one of many types of valves suitable for the purpose, reference is made to the P. S. Russel US. Patent No. 1,786,402, granted December 23, 1930. The valve of said patent, when mounted as shown in Fig. 1, provides for the taking off of oil to the burner from the lower part of the casing and for the taking off of oil to the by-pass from the highest point of the casing where the air and air-laden oil accumulate.

The function of the device 29' is to divide the stream of excess oil bypassed by valve 23 through pipe 25, and return a certain part, preferablyjhe smaller part, to the tank I5 by way of-pipe 26 and another, and preferably the larger part, to the pump by way of pipe 2 I larger and counterbored part of passage 28 to the pipe'26. Such oil as is returned to the supply tank I5 has to pass the ball valve 33. Preferably, the

seat for valve 39 is scored or otherwise formed,

to permit a constant although-small amount of "oil to pass the valve even when the latter is held to its seat. This allows the pressure in the system to drop to zero when the pump is stopped and is desirable for other reasons as pointed out in the Russel patent which also discloses a groove in the by-pass valve of the device 23,

The branch passage 29 leads downwardly to and intersects with a horizontal passage 34, which at one end connects with the suction pipe I9 and at the other end intersects With a vertical passage 35, the upper end of which is closed by a plug 36. The outlet, closed by plug 35, is provided to receive a vacuum gauge when one is'de'sired. Intermedistrength than spring 3|.

which is mounted for vertical sliding movement 5 in a hole 41! formed in a screw 4|, threaded into the interior of a hollow hub 42. vA spring 43, mounted in hole 40, acts between the closed lower end of screw 4| and the lower end of shank 39 tending to hold valve 38 closed. A portion of shank 39 is milled off forming a flattened side 44 and the milling cut is extended into the valve head 38, forming a groove 44. This groove 44 and the recess formed by cutting away a portion of shank 39 enable constant communication between the interior of hole 49 and the passage 34 so that the valve shank 39 may slide freely back and forth in hole 40. The screw 4| is normally concealed by a cap nut 45. By removing nut 45, screw 4| may be turned with a screw driver to raise or lower its upper end, such end acting as-an abutment engageable by the valve head 38 to limit the degree of its opening movement.

In operation, the pump I3 draws up oil from tank I5 through pipe I8, strainer II, pipe I9, pas- 2 5 sages 34, 35 and 37 and pipe 2| and forces such oil through pipe'22 into the valve-23. When-sufficient pressure has been built up, oil is permitted to flow into piping 24 and thus to nozzle I6. .If, as is usual, the pump supplies oil at a rate .in excess of that at which it is used by the burner, the.pres sure soon builds up in casing 23 above the prede- 'termined pressure desired for the supply of. oil. to the nozzle and then-the excess oil is permitted to flow out through pipe 25. Such by-passed oil enters passages 21 and 29 and the inner end of passage 29. The spring 43 is a light one and of less Consequently, the valve 38 will open before valve 30. .As a matter .of fact, it opens almost immediately when oil enters ,pas- 4 all! --sage 29, the spring 43 being just strong enough-to hold the valve closed when there is no oil being by-passed. Then valve 38 opens to the limit permitted by the upper end of screw 4|.

The valve 38. has a metering function in that, 45

when open to the limit allowed by screw 4|, it

gauges the size of the opening through whichbypassed oil may flow to the suction side of the pump. As much by-passed oil flows back to the pump, as is permitted by the effective area of this opening andthe prevailing conditions of temperatureand pressure. In accomplishing this function, the valve might be fixed in its open position or other means used for providing an orifice of the desired size. However, it is preferable to have the arrangementdisclosed because the valve will close off communication of the pumpsuction passage 34 with passage 29 when the pump stops and avoid what would otherwise be a bad leak in the suction line when the pump starts up. Such of the by-passed oil as cannot pass through the restricted outlet opening of passage 29 leaves by way of passage 28, forcing valve 39 to open. This passage 28 is located at a higher point in the by-pass line than the outlet of passage29 so as to carry off the air and air-laden oil. The valve 30, however, does not open until valve-38 has been opened to the limit available and then only when oil inexcess of the capacity-of the aforesaid restricted outlet is flowing in-passageZ'I. 7 0

By proper'adjustment of the screw 4| and the extent of opening of valve 38 for any givenrate or fiowofby-passed oil in pipe 25, such oil can be divided into two streams-of such relative. proportions as are desired. For example, assume that the capacity of the pump I3 is gallons per hour and only 10 gallons per hour are used at the nozzle, the balance,--30 gallons per hour,- is by-passed by valve 23 into pipe 25. Then valve 38 may be adjusted so that per cent of the volume of the by-passed oil, or 27 gallons, will flow into the suction passage 34 and the remainder, or 3 gallons, will have to leave by way of passage 28 and be returned to the tank.

From this one example, the importance of the invention will be appreciated. Far less oil is drawn through strainer IT in a given time than would be the case if all the by-passed oil were returned to tank 15 in accordance with prior practice. Less frequent cleaning of the strainer will be required. Far less oil will be returned to tank l5 to cause agitation of the oil therein and the undesirable stirring up of sludge therein. And, since less oil is drawn through the strainer in any given time, less work will be required of the pump. Much of the excess oil is returned to the suction side of the pump and therefore less oil has to be pulled up by suction from tank IS in any given time.

It will thus be seen that the invention provides for the ridding of air from the system without requiring all of the by-passed oil to be returned to the tank, as heretofore. The desired object is accomplished with a minimum waste of pumped oil and without making the strainer perform as much work as formerly,

What we claim is:

1. A device of the class described, comprising a casing having an inlet and outlet and a passage connecting the inlet and outlet for the flow of liquid in one direction therethrough, said casing having a second inlet, a second outlet and a second connecting passage for the flow of liquid therethrough in a reverse direction, said second passage having a part overlying a part of the first passage and said casing having a third passage interconnecting said parts with an inlet 5 at its upper end from the second passage and an outlet at its lower end into the first passage,

a valve for the last named outlet, resilient means efiective to close the valve and hold it closed until the pressure in the third passage exceeds 10 that in the first passage by a predetermined degree, and means for limiting the extent of opening of said valve under the pressure of liquid in said third passage.

2. A device of the class described, comprising, 15 a casing having an inlet and outlet and a passage connecting the inlet and outlet for the flow of liquid in one direction therethrough, said casing having a second inlet, a second outlet and a second connecting passage for the flow of liquid 20 therethrough in a reverse direction, said second passage having a part overlying a part of the first passage and said casing having a third passage interconnecting said parts with an inlet at its upper end from the second passage and an 25 outlet at its lower end into the first passage, a valve located between the inlet of the third passage and the outlet of the second passage for closing said second passage, said valve opening in response to pressure of liquid in the second pas- 30 sage above a predetermined degree, and a valve for closing the outlet of the third passage and opening in response to pressure in the third passage of a less degree, and means for limiting the extent of opening of the second valve. 35.

LEOLYN F. SPE'AR. VIRGIL E. DUEMLER.

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